# Storage block

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|  | This documentation is for<br>a previous<br>version of Cerbos. Choose 0.53.0 from the version picker at the top right or navigate to [https://docs.cerbos.dev](https://docs.cerbos.dev/) for the latest version. |

Cerbos supports multiple backends for storing policies. Which storage driver to use is defined by the `driver` setting.

## Disk driver

The disk driver is a way to serve the policies from a directory on the filesystem. Any `.yaml`, `.yml` or `.json` files in the directory tree rooted at the given path will be read and parsed as policies.

Static fileset with no change detection

```yaml
storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies
```

Dynamic fileset with change detection

```yaml
storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies
    watchForChanges: true
```

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|  | On some platforms the automatic change detection feature can be inefficient and resource-intensive if the watched directory contains many files or gets updated frequently. |

### Archive Files

Alternatively, you can opt to archive and/or compress your policies directory into a Zip (`.zip`), Tar (`.tar`) or Gzip file (`.tgz` or `.tar.gz`). The archive is assumed to be laid out like a standard policy directory. It must contain no non-policy YAML files.

You specify the file in your config like so:

Archived fileset using a Zip file

```yaml
storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies.zip
```

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|  | Change detection will be disabled when using archive files. |

## Blob driver

Cerbos policies can be stored in AWS S3, Google Cloud Storage, or any other S3-compatible storage systems such as [Minio](https://www.minio.io/).

Configuration keys

- `bucket`: Required. A URL specifying the service (e.g. S3, GCS), the storage bucket and any other configuration parameters required by the provider.

- AWS S3: `s3://my-bucket?region=us-west-1`. Must specify region in the URL.
  - Google Cloud Storage: `gs://my-bucket`
  - S3-compatible (e.g. Minio): `s3://my-bucket?endpoint=my.minio.local:8080&disableSSL=true&s3ForcePathStyle=true&region=local`. Must specify region in the URL.

- `prefix`: Optional. Look for policies only under this key prefix.
- `workDir`: Optional. Path to the local directory to download the policies to. Defaults to the system cache directory if not specified.
- `updatePollInterval`: Optional. How frequently the blob store should be checked to discover new or updated policies. Defaults to 0 — which disables polling.
- `requestTimeout`: Optional. HTTP request timeout. It takes an HTTP request to download a policy file. Defaults to 5s.
- `downloadTimeout`: Optional. Timeout to download all policies from the storage provider. Must be greater than the `requestTimeout`. Defaults to 60s.

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|  | Setting the `updatePollInterval` to a low value could increase resource consumption in both the client and the server systems. Some managed service providers may even impose rate limits or temporary suspensions on your account if the number of requests is too high. |

...

### Git driver

Git is the preferred method of storing Cerbos policies. The server is smart enough to detect when new commits are made to the git repository and refresh its state based on the changes.

Local git repository

```yaml
storage:
  driver: "git"
  git:
    protocol: file
    url: file://${HOME}/tmp/cerbos/policies
    checkoutDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 10s
```

Remote git repository accessed over HTTPS

```yaml
storage:
  driver: "git"
  git:
    protocol: https
    url: https://github.com/cerbos/policy-test.git
    branch: main
    subDir: policies
    checkoutDir: ${HOME}/tmp/work/policies
    updatePollInterval: 60s
    operationTimeout: 30s
    https:
      username: cerbos
      password: ${GITHUB_TOKEN}
```

## SQLite3 Driver

The SQLite3 storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.33.0/configuration/server#admin-api).

In-memory ephemeral database

```yaml
storage:
  driver: "sqlite3"
  sqlite3:
    dsn: ":memory:"
```

On-disk persistent database

```yaml
storage:
  driver: "sqlite3"
  sqlite3:
    dsn: "file:/tmp/cerbos.sqlite?mode=rwc&cache=shared&_fk=true"
```

## Postgres Driver

The Postgres storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.33.0/configuration/server#admin-api).

Using Postgres as a storage backend for Cerbos

```yaml
storage:
  driver: "postgres"
  postgres:
    url: "postgres://${PG_USER}:${PG_PASSWORD}@localhost:5432/postgres?sslmode=disable&search_path=cerbos"
```

...

## Microsoft SQL Server Driver

The SQL Server storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.33.0/configuration/server#admin-api).

Using SQL Server as a storage backend for Cerbos

```yaml
storage:
  driver: "sqlserver"
  sqlserver:
    url: "sqlserver://${SQL_SERVER_USERNAME}:${SQL_SERVER_PASSWORD}@host/instance?database=cerbos&param1=value&param2=value"
```

### Connection pool

Cerbos uses a connection pool when connecting to a database. You can configure the connection pool settings by adding a `connPool` section to the driver configuration.

Available options are:
- `maxLifeTime`
- `maxIdleTime`
- `maxOpen`
- `maxIdle`

```yaml
storage:
  driver: "sqlserver"
  sqlserver:
    url: "sqlserver://${SQL_SERVER_USERNAME}:${SQL_SERVER_PASSWORD}@host/instance?database=cerbos&param1=value&param2=value"
    connPool:
      maxLifeTime: 5m
      maxIdleTime: 3m
      maxOpen: 10
      maxIdle: 5
```

### Redundancy

You can provide redundancy by configuring an `overlay` driver, which wraps a `base` and a `fallback` driver. Under normal operation, the base driver will be targeted as usual. However, if the driver consistently errors, the PDP will start targeting the fallback driver instead.